Various types of steering railway trucks have been proposed wherein the angular position of the axles and their associated wheels are allowed or forced to adjust during curve negotiation to maintain more or less radial positions with respect to the curve. The purpose of such arrangements is, generally, to reduce friction and wear of wheels and rails by minimizing lateral creep forces. While most applications have been proposed for non-powered railway car, trucks, some locomotive applications have also been proposed.
Prior steering railway trucks have included some having soft primary suspensions which allow relatively free longitudinal and/or lateral motion of the wheel and axle assemblies within established limits. Some arrangements include inter-axle connections that require related motions among axles of the same truck. Some of the arrangements are such that lateral wheel and axle motion gives rise to forced yaw or steering, whereas other arrangements substantially isolate these functions. Both powered and unpowered axles have been arranged for steering; however, forced steering of powered axle vehicles relative to truck turning motion in relation to the carbody is common.